Time division communication system

Abstract

A time division communication system where particular codes are added to modulation input data corresponding to front and rear edges of a data burst so that the modulated wave in the front and rear edges of the data burst from the station becomes a 100 percent amplitude modulated wave. By making use of the characteristic that the amplitude element is superimposed on the modulated wave signal during phase modulation and amplitude modulation, switching is performed at the point where the amplitude of the modulated wave becomes zero and the switched signal is inserted in a time slot assigned thereto.

I claim: 
     
       1. A time dividing communication system for transmitting modulation data that has been band limited, comprising: modulation means, for modulating the modulation input data after the band limitation, where the modulation data is phase modulated or amplitude modulated and thereafter transmitted as a burst signal in an assigned time slot;   code adding means, operatively connected to receive the modulation input data and to said modulation means, for adding particular codes to the modulation input data so that the modulated wave becomes a waveform having received a 100% amplitude modulation corresponding to front and rear edges of the modulation input data;   switching means, operatively connected to said modulation means, for switching the modulated wave at a zero amplitude modulation point and inserting the modulated wave in the assigned time slot; and   said modulation means comprising a driving modulator and when executing phase modulation or amplitude modulation of said modulation input data, an offset voltage of the driving modulator is changed only during the period corresponding to the front and rear edges of the modulation input data including the particular codes and the switching by said switching means is carried out at the point where amplitude of said modulated wave becomes zero.   
     
     
       2. A time dividing communication system for transmitting modulation data that has been band limited, comprising: modulation means, for modulating the modulation input data after the band limitation, where the modulation data is phase modulated or amplitude modulated and thereafter transmitted as a burst signal in an assigned time slot, said modulation means comprising: a modulator driving circuit, operatively connected to said code adding means;     code adding means, operatively connected to receive the modulation input data and to said modulation means, for adding particular codes to the modulation input data so that the modulated wave becomes a waveform having received a 100% amplitude modulation corresponding to front and rear edges of the modulation input data; and switching means, operatively connected to said modulation means, for switching the modulated wave at a zero amplitude modulation point and inserting the modulated wave in the assigned time slot, said modulation input data being transmitted as the burst signal and said code adding means adding particular codes to said modulation input data that provide the same data bit condition continuing at least two bits or more at the front edge of said burst signal and the same bit condition continuing at least for two bits or more at the rear edge of said burst signal, and for providing a constant offset voltage at least during the period corresponding to the front and rear edges of the burst signal, and a changed offset voltage at the point where the amplitude of said modulated wave becomes zero.     
     
     
       3. A time dividing communication system for transmitting modulation data that has been band limited, comprising: modulation means, for modulating the modulation input data after the band limitation, where the modulation data is phase modulated or amplitude modulated and thereafter transmitted as a burst signal in an assigned time slot;   code adding means, operatively connected to receive the modulation input data and to said modulation means, for adding particular codes to the modulation input data so that the modulated wave becomes a waveform having received a 100% amplitude modulation corresponding to front and rear edges of the modulation input data; and   switching means, operatively connected to said modulation means, for switching the modulated wave at a zero amplitude modulation point and inserting the modulated wave in the assigned time slot, said modulation input data being transmitted as the burst signal and said code adding means adding particular codes to said modulation input data that provide the same data bit condition continuing at least two bits or more at the front edge of said burst signal and the same bit condition continuing at least for two bits or more at the rear edge of said burst signal, said switching means comprising: a filter circuit connected to receive and ON/OFF control signal;   an amplifier connected to said filter; and   a switching circuit including: a first capacitor operatively connected to said modulation means;   an inductor operatively connected to said amplifier;   a switching diode operatively connected to said first capacitor, said inductor and ground; and   a second capacitor operatively connected to said first capacitor, said inductor and said switching diode, rising and falling edges of the ON/OFF signal for switching are shaped by said filter circuit during the switching of said modulated wave and thereafter said ON/OFF control signal is input to said amplifier having a low output impedance and the switching is realized by controlling a current of said switching diode using said amplifier output.       
     
     
       4. A time dividing communication system for transmitting modulation data that has been band limited, comprising: modulation means, for modulating the modulation input data after the band limitation, where the modulation data is phase modulated or amplitude modulated and thereafter transmitted as a burst signal in an assigned time slot;   code adding means, operatively connected to receive the modulation input data and to said modulation means, for adding particular codes to the modulation input data so that the modulated wave becomes a waveform having received a 100% amplitude modulation corresponding to front and rear edges of the modulation input data; and   switching means, operatively connected to said modulation means, for switching the modulated wave at a zero amplitude modulation point and inserting the modulated wave in the assigned time slot, said modulation input data being transmitted as the burst signal and said code adding means adding particular codes to said modulation input data that provide the same data bit condition continuing at least two bits or more at the front edge of said burst signal and the same bit condition continuing at least for two bit or more at the rear edge of said burst signal, said switching means comprising: an integral circuit and a differential circuit operatively connected to receive an ON/OFF control signal;   a first capacitor operatively connected to said modulation means;   an inductor operatively connected to said integral circuit and said differential circuit;   a switching diode operatively connected to said first capacitor, said inductor and ground; and   a second capacitor operatively connected to said first capacitor, said inductor and said diode, during the switching of said modulated wave, the ON/OFF control signal for switching is shaped by said integral circuit, it is combined with the signal obtained by differentiating the falling edge of said ON/OFF signal, and a current of said switching diode is controlled by said combined output and thereby the switching is carried out.     
     
     
       5. A time division communication system, comprising: control signal means for generating control signals;   code signal generation means, operatively connected to said control signal means, for generating front and rear code signals for the data signal in dependence upon the control signals, the front and rear code signals each having zero crossing;   hybrid means, operatively connected to receive the data signal and to the code signal generation means, for producing a combined signal from the data signal and the front and rear code signals;   modulation means, operatively connected to said hybrid means and said control signal means, for modulating the combined signal with a carrier, said modulation means comprising: driver means, operatively connected to said hybrid means and said control signal means, for outputting an amplified signal in dependence upon the combined signal and the control signals; and   a modulator, operatively connected to said drive means and said switch means, for modulating the amplified signal with the carrier; and     switch means, operatively connected to said modulation means and said control signal means, for switching therethrough the modulated combined signal in synchronism with the zero crossing of the front and rear code signals in the modulated combined signal, said driver means including offset means for adjusting the zero crossing coincident with the switching by said switch means.   
     
     
       6. A time division communication system according to claim 5, wherein said driver means comprises: a gate circuit operatively connected to said hybrid means;   an offset circuit operatively connected to said control signal means; and   an amplifier operatively connected to said gate circuit, said offset circuit and said modulator.   
     
     
       7. A time division communication system according to claim 5, wherein said driver means comprises: a gate circuit operatively connected to said hybrid means;   a switch circuit operatively connected to said gate circuit and said control signal means;   an offset circuit operatively connected to said control signal means; and   an amplifier operatively connected to said switch circuit, said offset circuit and said modulator.   
     
     
       8. A time division communications system according to claim 5, wherein said driver means comprises: a shift register operatively connected to said hybrid means and said control signal means;   resistors operatively connected to said shift register;   an offset circuit operatively connected to said control signal means; and   an amplifier operatively connected to said offset circuit, said resistors, and said modulator.   
     
     
       9. A time division communication system according to claim 5, wherein said modulation means further comprises a filter operatively connected between said driver means and said modulator. 
     
     
       10. A time division communication system according to claims 5, 6, 7 or 8, wherein said modulator comprises a balance mixer operatively connected to said driver means and said switch means. 
     
     
       11. A time division communication system according to claim 5, wherein said switch means comprises: a first capacitor operatively connected to said modulator means;   an inductor operatively connected to said control signal means;   a diode operatively connected to said first capacitor, said inductor and ground; and   a second capacitor operatively connected to said first capacitor, said inductor and said diode.   
     
     
       12. A time division communication system according to claim 5, wherein said system is a four phase modulation system, said data signal comprises first and second data signals, said hybrid means comprises first and second hybrid means, each operatively connected to said control signal means and each for producing a combined signal from the respective data signals and the front and rear code signals, and said modulation means comprises first and second modulation means each connected to the respective first and second hybrid means and to said control circuit means, each for modulating the respective combined signal with a carrier,   wherein said system further comprises data signal hybrid means, operatively connected to said first and second modulation means and said switch means, for combining the modulated signals produced by said first and second modulation means, and   wherein said each of said first and second modulation means comprises: driver means, operatively connected to the respective said hybrid means and said control signal means, for outputting an amplified signal in dependence upon the respective combined signal and the control signals; and   a modulator, operatively connected to said driver means and said data signal hybrid means, for modulating the amplified signal with the carrier.     
     
     
       13. A time division communication system according to claim 12, wherein said driver means comprises: a gate circuit operatively connected to the respective said hybrid means;   an offset circuit operatively connected to said control signal means; and   an amplifier connected to said gate circuit, said offset circuit and said modulator.   
     
     
       14. A time division communication system according to claim 12, wherein said driver means comprises: a gate circuit operatively connected to the respective said hybrid means;   a switch circuit operatively connected to said gate circuit and said control signal means;   an offset circuit operatively connected to said control signal means; and   an amplifier operatively connected to said switch circuit, said offset circuit and said modulator.   
     
     
       15. A time division communication system according to claim 12, wherein said driver means comprises: a shift register operatively connected to the respective said hybrid means and said control signal means;   resistors operatively connected to said shift register;   an offset circuit operatively connected to said control signal means; and   an amplifier operatively connected to said offset circuit, said resistors, and said modulator.   
     
     
       16. A time division communication system according to claim 12, wherein each said modulation means further comprises a filter operatively connected between said driver means and said modulator. 
     
     
       17. A time division communication system according to claim 12, wherein said control signal means comprises: a gate circuit;   a filter operatively connected to said gate circuit; and   an amplifier operatively connected to said filter and said switch means.   
     
     
       18. A time division communication system according to claim 12, wherein said control signal means comprises: a gate circuit;   a differential circuit operatively connected to said gate circuit;   an integral circuit operatively connected to said gate circuit; and   an amplifier operatively connected to said differential circuit, said integral circuit and said switch means.   
     
     
       19. A time division communications system according to claim 12, wherein said switch means comprises: a first capacitor operatively connected to said data signal hybrid means;   an inductor operatively connected to said control signal means;   a diode operatively connected to said first capacitor, said inductor and ground;   a second capacitor operatively connected to said first capacitor, said inductor and said diode.   
     
     
       20. A time dividing communication system according to claims 1 or 2, wherein said switching means comprises: a filter circuit connected to receive an ON/OFF control signal;   an amplifier connected to said filter; and   a switching circuit including: a first capacitor operatively conneeted to said modulation means;   an inductor operatively connected to said amplifier;   a switching diode operatively connected to said first capacitor, said inductor and ground; and   a second capacitor operatively connected to said first capacitor, said inductor and said switching diode rising and falling edges of the ON/OFF signal for switching are shaped by said filter circuit during the switching of said modulated wave and thereafter said ON/OFF control signal is input to said amplifier having a low output impedance and the switching is realized by controlling a current of said switching diode using said amplifier output.     
     
     
       21. A time dividing communication system according to claims 3 or 5, wherein said switching means comprises: an integral circuit and a differential circuit operatively connected to receive an ON/OFF control signal;   a first capacitor operatively connected to said modulation means;   an inductor operatively connected to said integral circuit and said differential circuit;   a switching diode operatively connected to said first capacitor, said inductor and ground; and   a second capacitor operatively connected to said first capacitor, said inductor and said diode, during switching of said modulated wave, the ON/OFF control signal for switching is shaped by said integral circuit and combined with the signal obtained by differentiating the falling edge of said ON/OFF signal, and a current of said switching diode is controlled by said combined output and thereby the switching is carried out.